There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an uncommon telephone from an irrigator within the late 1990’s. “Rob”, he mentioned, “I assume there’s a wheel barrow in my pipeline. Can you find it?”

Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant

Wheel barrows were used to carry package for reinstating cement lining throughout delicate metal cement lined (MSCL) pipeline building in the outdated days. It’s not the first time Rob had heard of a wheel barrow being left in a large pipeline. เกจวัดแรงดัน has it that it happened in the course of the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It can be suspected that it may just have been a plausible excuse for unaccounted friction losses in a model new 1000mm trunk main!

Rob agreed to assist his shopper out. A 500mm dia. PVC rising major delivered recycled water from a pumping station to a reservoir 10km away.
The drawback was that, after a yr in operation, there was a few 10% reduction in pumping output. The shopper assured me that he had examined the pumps and so they have been OK. Therefore, it simply had to be a ‘wheel barrow’ in the pipe.
READ: Cheaper irrigation strategies for worthwhile farming

Rob approached this downside a lot as he had throughout his time in SA Water, the place he had extensive experience locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines through the 1980’s.
Recording hydraulic gradients

He recorded correct pressure readings alongside the pipeline at a quantity of areas (at least 10 locations) which had been surveyed to offer accurate elevation information. The sum of the strain studying plus the elevation at each point (termed the Peizometric Height) gave the hydraulic head at each level. Plotting the hydraulic heads with chainage provides a a quantity of point hydraulic gradient (HG), very like in the graph below.
Hydraulic Grade (HG) blue line from the friction checks indicated a constant gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow within the pipe, the HG could be just like the purple line, with the wheel barrow between factors 3 and 4 km. Graph: R Welke

Given that the HG was pretty straight, there was clearly no blockage along the means in which, which would be evident by a sudden change in slope of the HG at that time.
So, it was figured that the pinnacle loss should be because of a basic friction construct up within the pipeline. To verify this principle, it was determined to ‘pig’ the pipeline. This involved using the pumps to pressure two foam cylinders, about 5cm bigger than the pipe ID and 70cm lengthy, along the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline performance was improved 10% as a result of ‘pigging’. Photo: R Welke

The prompt improvement within the pipeline friction from pigging was nothing in need of wonderful. The system head loss had been virtually completely restored to unique efficiency, leading to a few 10% circulate improvement from the pump station. So, instead of finding a wheel barrow, a biofilm was found liable for pipe friction build-up.

Pipeline efficiency may be at all times be seen from an vitality effectivity perspective. Below is a graph exhibiting the biofilm affected (red line) and restored (black line) system curves for the client’s pipeline, before and after pigging.
READ: 5 Factors to think about when choosing irrigation pump

The improve in system head as a outcome of biofilm brought on the pumps not solely to operate at a higher head, however that a variety of the pumping was forced into peak electricity tariff. The decreased performance pipeline in the end accounted for about 15% extra pumping vitality costs.
Not everyone has a 500NB pipeline!

Well, not everybody has a 500mm pipeline of their irrigation system. So how does that relate to the typical irrigator?

A new 500NB

System curve (red line) indicates a biofilm build-up. Black line (broken) reveals system curve after pigging. Biofilm raised pumping prices by up to 15% in one year. Graph: R Welke

PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When decreased to C=140 (10%) via biofilm build-up, the pipe could have the equal of a wall roughness of 0.13mm. The identical roughness in an 80mm pipe represents an H&W C value of 130. That’s a 16% reduction in flow, or a 32% friction loss enhance for a similar flow! And that’s simply within the first year!

Layflat hose can have high energy cost

A living proof was observed in an energy efficiency audit carried out by Tallemenco recently on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a soft hose boom had a head loss of 26m head in contrast with the manufacturers ranking of 14m for the same flow, and with no kinks within the hose! That’s a whopping 85% improve in head loss. Not shocking considering that this layflat was transporting algae contaminated river water and lay within the scorching solar all summer time, breeding these little critters on the pipe inside wall.
Calculated when it comes to vitality consumption, the layflat hose was liable for 46% of complete pumping power costs via its small diameter with biofilm build-up.
Solution is bigger pipe

So, what’s the solution? Move to a bigger diameter hose. A 3½” hose has a new pipe head lack of only 6m/200m at the same circulate, but when that deteriorates due to biofilm, headloss could rise to solely about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping vitality costs*. In terms of absolute energy consumption, if pumping 50ML/yr at 30c/kWh, that’s a saving of $950pa, or $10,700 over 10 years.
Note*: The pump impeller would must be trimmed or a VFD fitted to potentiate the energy financial savings. In some cases, the pump could should be modified out for a lower head pump.
Everyone has a wheel barrow in their pipelines, and it solely will get bigger with time. You can’t get rid of it, however you can management its results, either by way of power efficient pipeline design in the first place, or try ‘pigging’ the pipe to eliminate that wheel barrow!!

As for the wheel barrow in Rob’s client’s pipeline, the legend lives on. “He and I nonetheless joke concerning the ‘wheel barrow’ within the pipeline after we can’t explain a pipeline headloss”, said Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and by no means offered product in his life! He spent 25 yrs working for SA Water (South Australia) within the late 60’s to 90’s where he conducted extensive pumping and pipeline power effectivity monitoring on its 132,000 kW of pumping and pipelines infrastructure. Rob established Tallemenco Pty Ltd (2003), an Independent Pumping and Hydraulics’ Consultancy primarily based in Adelaide, South Australia, serving clients Australia extensive.
Rob runs common “Pumping System Master Class” ONLINE coaching courses Internationally to move on his wealth of data he realized from his fifty two years auditing pumping and pipeline systems all through Australia.
Rob could be contacted on ph +61 414 492 256, or e-mail . LinkedIn – Robert L Welke


Scroll to Top